The present invention relates to a magnetic head device set in sliding contact with a surface of a disk such as a magnetic disk or a magneto-optical disk that is used as a recording medium. The present invention also relates to a recording/reproducing apparatus, which uses this magnetic head device.
Hitherto known is a recording/reproducing apparatus which uses, as a recording medium, a magneto-optical disk that comprises a substrate transparent to light and a magneto-optical recording layer formed on the substrate and composed of a perpendicular magnetizing film. The recording/reproducing apparatus comprises a disk drive mechanism, a magnetic head device, and an optical pickup device. The disk drive mechanism rotates the magneto-optical disk. The magnetic head device is arranged at one side of the magneto-optical disk to apply an external magnetic field to the magneto-optical recording layer of the disk. The optical pickup device applies a light beam to the magneto-optical recording layer provided on that side of the magneto-optical disk. In the recording/reproducing apparatus, the magnetic head device applies a magnetic field to the magneto-optical recording layer of the magneto-optical disk being rotated. The magnetic field thus applied has a direction modulated in accordance with the data signal to be recorded on the magneto-optical disk. In addition, the light beam emitted from the optical pickup device is converged and applied to the magneto-optical recording layer. Applied with the light beam, the magneto-optical recording layer is heated to Curie point. Those parts of the layer which have lost coersive force, are magnetized in the direction of the magnetic field applied from the magnetic head device. Thereafter, the temperature of the magneto-optical recording layer falls below Curie point as the light beam moves relative to the magneto-optical disk that keeps rotating. The direction of the magnetic field is fixed in the layer, whereby the data signal is recorded on the magneto-optical disk.
The magnetic head device for applying a magnetic field to the magneto-optical recording layer of the magneto-optical disk has a head section 101 as shown in FIG. 1. The head section 101 comprises a magnetic field generating section 105 and a slider 106. The slider 106 holds the magnetic field generating section 105. The section 105 is composed of a magnetic core 102, a coil 103, and a bobbin 104. The coil 103 is wound around the bobbin 104.
The magnetic core 102, which is one component of the magnetic field generating section 105, comprises a center pole core 102a and a pair of side pole cores 102b, and a coupling section 102c. The side pole cores 102b are arranged on one side of the center pole core 102a and the other side thereof, respectively. The coupling section 102c connects the center pole core 102a and the side pole cores 102b at their proximal ends. The magnetic core 102 is shaped like letter E, as a whole. The bobbin 104 has an upper flange section 104a and a lower flange section 104b. Both flange sections 104a and 104b have a through hole, through which the center pole core 102a of the magnetic core 102 extends. The center pole core 102a of the magnetic core 102 passes through the holes of the flange sections and the coil 103 is wound around the center pole core 102a and made integral therewith. The magnetic field generating section 105 is thereby formed.
The slider 106, which holds the magnetic field generating section 105, is made of synthetic resin by means of injection molding. The slider 106 has a holder section 107 at its proximal end, for holding the magnetic field generating section 105. The slider 106 has a sliding-contact section 108 extending from the distal end of the holder section 107. The sliding-contact section 108 may be set into sliding contact with a magneto-optical disk. The holder section 107 has a recess, in which the magnetic field generating section 105 is fitted. Thus, the section 105 is connected to the holder section 107.
In the head section 101 of the magnetic head device, a gap of about 0.1 mm is formed between the magnetic field generating section 105 and the holder section 107. This is inevitable because the section 105 is fitted in the holder section 107 of the slider 106. As a consequence, very little heat generated by the magnetic core 102 is radiated through the slider 106.
In the head section 101, the drive current and the record/transfer speed may be increased so that the magnetic field generating section 105 generates a more intense magnetic field. If so, the copper loss or iron loss of the coil 103 will increase, resulting in a further increase in the heat generated by the magnetic core 102 or the coil 103. When the temperature of the magnetic core 102 or coil 103 rises to a value near Curie point, the magnetic permeability inevitably decreases, reducing the intensity of the magnetic field generated. Moreover, inter-layer short-circuiting occurs in the coil 103 when the temperature of the magnetic core 102 or coil 103 rises further, possibly resulting in burning. It is therefore impossible in the head section 101 to intensity the magnetic field or raise the record/transfer speed.
Furthermore, the head section 101 cannot increase the minimum intensity guaranteed for the magnetic field. This is inevitable because the tolerances of the components are limited since the magnetic field generating section 105 must be fitted in the slider 106.
Accordingly it is the object of the present invention to provide a magnetic head device in which heat can be efficiently radiated from the head section and the minimum intensity guaranteed for the magnetic field can be increased, and also a recording/reproducing apparatus which uses this magnetic head device.
A magnetic head device according to the present invention comprises a head section for applying a magnetic field to a disk. The head section includes a magnetic field generating section and a slider supporting the magnetic field generating section and is designed to be set in sliding contact with the disk. The magnetic field generating section has a magnetic core and a coil wound around the magnetic core. The magnetic field generating section generates the magnetic field and is embedded in and formed integral with the slider.
The head section has been formed by placing the magnetic field generating section at a prescribed position in a metal mold and then filling the metal mold with the material of the slider. The metal mold has a positioning projection. The projection is to abut on a distal end of the magnetic core, which opposes the disk, thereby to position the magnetic field generating section in a direction substantially perpendicular to the disk. A coil is wound around a bobbin that is mounted on the magnetic core. The bobbin has positioning projections to abut on sides of a metal mold for forming the head section, thereby to position the magnetic field generating section in a direction substantially parallel to the disk. Thus, the magnetic field generating section is arranged at the prescribed position in the metal mold.
A recording/reproducing apparatus according to the present invention comprises a magnetic head device. The magnetic disk device comprises a disk driving mechanism and a magnetic head mechanism. The disk driving mechanism rotates a disk. The magnetic head mechanism is provided on one side of the disk and comprises a head section for applying a magnetic field to a disk. The head section includes a magnetic field generating section and a slider supporting the magnetic field generating section and is designed to be set in sliding contact with the disk. The magnetic field generating section has a magnetic core and a coil wound around the magnetic core, for generating the magnetic field. The magnetic field generating section is embedded in and formed integral with the slider. The recording/reproducing apparatus may further comprise an optical pickup device provided on the other side of the disk and opposing the head section, for applying a light beam to the other side of the disk.
According to the present invention, the magnetic field generating section and the slider are formed integral with each other. The heat generated by the magnetic field generating section can therefore be radiated with high efficiency. The magnetic field generated by the magnetic field generating section can increase in intensity, without damaging the magnetic field generating section, and the record/transfer speed can be enhanced. Moreover, since the magnetic field generating section and the slider are formed integral in the head section, the tolerances of the components need not be taken into consideration, and the minimum intensity guaranteed for the magnetic field can yet be increased.